


the blood which we drew

by dothraki_shieldmaiden



Category: Supernatural
Genre: 15.09 coda, 15.09 spoilers, Angst, Castiel Bears the Mark of Cain (Supernatural), Multi, Not A Fix-It, Not A Happy Ending, Not major character death but kind of, moc!castiel, sorry kids
Language: English
Status: Completed
Published: 2020-01-20
Updated: 2020-01-20
Packaged: 2021-02-26 08:08:58
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 7,335
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22326217
Author URL: https://archiveofourown.org/users/dothraki_shieldmaiden/pseuds/dothraki_shieldmaiden
Summary: Castiel bears the Mark. And for a few months, it's fine.It's fine until it isn't.
Relationships: Castiel/Dean Winchester, Eileen Leahy/Sam Winchester
Comments: 43
Kudos: 192





	the blood which we drew

**Author's Note:**

> Because I'm awful and have no kindness left in me...read this. It's sad and angsty and awful. 
> 
> Not beta-read, we die like men in this house.

\---

_The mark of Cain is stamped upon our foreheads. Across the centuries, our brother Abel was lain in blood which we drew, and shed tears we caused by forgetting Thy love.--Pope John XXIII_

\---

Once the dust clears, once they determine that Chuck is really gone, once they lick their bleeding wounds clean, Dean reaches out for Cas’ arm. He pushes Cas’ sleeve up, much like Cas once did to him, and looks in at the pale skin of Cas’ forearm. 

The Mark sits on Cas’ skin, close to the location where it once sat on Dean’s arm. 

Unlike the livid red of the Mark of Cain, this mark is unobtrusive. It’s only slightly darker than Castiel’s skin, and if it weren’t for his prior knowledge, Dean could almost dismiss it as a birthmark. 

He can’t determine the shape. This mark doesn’t bear a resemblance to anything that he’s seen before. “It’s different,” Dean finally says, stupidly. He can’t stop staring at it. “I thought that it would be the same.” 

“No,” Castiel murmurs. His own eyes are trained to the blemish on the once perfect skin. “The Mark of Cain was created to cage The Darkness. It was born of something that was inherently malicious.” His fingers hover over the mark, like they want to touch it, but they’re afraid to. “Chuck...God...” Cas laughs mirthlessly. “Whatever he may have turned out to be, he didn’t begin as a malicious force. He began...” Castiel sighs. “It was good in the beginning. The idea of creation. Free will. It was good.” 

Dean’s fingertips inch up along the smooth skin of Cas’ arm. When they ghost over the mark, Cas’ breathing hitches. A small tremor shakes through his muscle. When Dean presses down more firmly on the mark, Cas’ arm twitches in his hands, like he wants to pull away, but he somehow resists. 

“Free will,” Dean says. He can’t stop looking at the mark. The lines of the mark twist and whorl on Cas’ skin and he can’t find either an ending or a beginning to them. He presses the pad of his thumb squarely in the middle of the mark. A soft cry falls from Cas’ lips. “Looks like we’ve got a lot more of that these days.” 

He strokes over the mark, eyes glued to the sharp lines. Full shivers wrack Cas’ body, but he doesn’t pull away, not even when Dean raises his arm upwards. “There’s a lot you can do with free will,” Dean says, before he presses his lips to the faint blue veins lurking under the thin skin of Cas’ wrists. He drags his lips up the line of Cas’ arm. By the time he kisses just underneath the mark, Cas’ breathing is raspy and audible. 

He presses a kiss to the center of the mark. There’s a faint tingle in his lips, like he’s been sucking on ghost peppers, the soft buzz of electricity humming through his skin. He’d thought that maybe it would taste different, that the skin would be raised, that he’d be flung across the room, _something_\--But there’s just the clean taste of Cas, fresh rainstorms and sweat on his tongue. 

But Cas--Cas reacts like Dean just zapped him with five thousand volts. The moment that Dean’s lips press to the mark, a sharp cry leaves his lips. His muscles tense and his left hand clamps down on Dean’s knee. 

Dean pulls back and finally looks up at Cas. Truth be told, he was afraid to look at Cas before--terrified that this mark would be like the last, and that he would look into Cas’ eyes and not see his angel looking back at him. 

But when he looks into Cas’ eyes, it’s still just the same Castiel looking back at him. Sure, he looks a little flushed and flustered, a little unstrung, but to be fair, Dean has been doing his best to make him that way. 

“Free will,” Dean says. His breath ghosts over the mark and this time he can watch how Cas’ eyes darken, how his pupils expand. “With Chuck gone...anything could happen.” 

He presses his thumb over the mark again, just to watch Cas shudder. Before Cas’ eyes close, he thinks that he might see _something_ swirling around the edges of Cas’ pupils, something ancient and cold, something that regards Dean and everyone else as only pawns in the course of a greater quest--But then a shaky smile spreads across Cas’ face and it’s just Cas in front of him. Just the angel that Dean’s helplessly in love with. 

“Anything?” Castiel asks, and Dean forgets what he thought he saw.

\---

And for months, it’s fine. 

Contrary to all of Chuck’s ravings, their world is _fine_ without him. Life continues the same way that it always has except, with perhaps a few, exceedingly welcome additions. Like, Eileen moves in permanently into the bunker. From there she moves into Sam’s bedroom. And Cas...Cas makes a similar horizontal shift, from his bare-bones excuse of a room into Dean’s much more well-decorated room. Dean shares his memory foam mattress with someone who has octopus limbs and who doesn’t technically sleep but who will do a damn good job of faking it when it comes time to do any sort of chores. 

And it’s fine. 

And sometimes Dean will wander in and Cas will be standing, stock-still in the middle of a room, head tilted like he’s listening to the fabric of the earth rumble, and he won’t respond when Dean calls his name. Dean will touch him on the elbow and it will take Cas an eternity to turn around, stiff-limbed like his arms and legs are appendages that he hasn’t learned how to work yet. And when Dean looks at Cas’ eyes, it’s just...it’s _empty_, but it’s not because there’s _something_ there, something ancient and calculating and so very very _vast_ that even though Dean is a few inches taller than Castiel he feels like he really is craning his head back to look at the top of the Chrysler building. 

And then Cas blinks, and he’s just _Cas_, just the weird, dorky guy who Dean has somehow inexplicably fallen in love with, and who more inexplicably, loves him back. 

And it’s fine. 

\---

It starts slow. 

The hunts start to pick up and the movie nights dwindle until Dean can’t remember the last time that the four of them were in the bunker for longer than it took to grab four hours of sleep, a meal, and a shower. Sam’s eyes are shadowed and, Dean realizes with a lurch, the hairs at his temples have turned a soft, gentle silver. Eileen’s lost weight and, where she used to coyly mention a house in town that looked like it had a nice backyard, she now mentions death tolls and body counts and witnesses. 

Ever since they got the news about Claire, none of them laugh much. 

But worse in a way is Cas. Cas, who starts to pull away from Dean, inch by inch. He never needed to sleep, but he would always stay in bed with Dean and allow Dean to pull him selfishly closer during the middle of the night. And when Dean awoke, Cas was always there--sometimes tapping away on a laptop, sometimes flipping through a paperback, sometimes watching something with the volume turned all the way down and subtitles on. Now, Dean wakes to a cold bed whose sheets don’t even hold the impression of another body. Whole days will go by without Cas talking to him, and Dean says that it’s the stress, that it’s the grief, that it’s the frustration, but then he’ll see Cas standing stock still on the roof in the middle of the night, his right forearm bare and the dark weight of foreboding will dip into his stomach--

“Cas,” Dean calls, deliberately vulnerable in just his robe and boxers, not even slippers on his feet. “Come to bed.” 

Cas turns and for a second--Dean can see the calculations rolling, the tumblers falling into place as this thing that is and isn’t Cas tries to place who he is--

And then Cas’ forehead creases in worry as his eyes flick over Dean’s form. “Dean, what are you...You’re not wearing shoes.” 

And despite the hard kernel of worry taking root in the pit of his stomach, despite the cold seeping into his body through the soles of his feet, Dean smiles, because it’s Cas who comes over to him, it’s Cas who ushers him downstairs with an exasperated fondness, it’s Cas who slides into bed behind him and doesn’t even grumble when Dean puts his cold feet against his shins. 

And Dean knows that everything’s going to be fine. 

\---

It’s the vamp’s nest that changes everything. 

Dean and Cas had gotten the call from Sam earlier that day--_It’s not just a few vamps Dean, there’s like thirty here, what the fuck is happening_\--and they’d hauled ass to get there. All through the drive, the tension had consumed the both of them. Cas had been quiet, a pensive look on his face as he rolled his shoulders in a continuous motion. 

They’d walked into a bloodbath, Sam and Eileen holed up in a closet with a dwindling supply of dead man’s blood, Eileen with a nasty cut on her forehead and Sam hobbling on what looked like a bad sprain if not an outright break. 

“Cas, I need you to--” Dean had said, dabbing at Eileen’s forehead. He’d meant for Cas to come over and heal Sam and Eileen so that they all stood a chance of making it out of there, but Cas ignored him. He walked with purpose towards the door, his face blank of everything and Dean hadn’t seen that look on his face since...Since thousands of souls were writhing in him and Cas obliterated an archangel with nothing more than a look. 

“Cas, what the hell do you think you’re doing?” Dean snaps, too worried about Sam, too worried about Eileen, too terrified of the way that Cas’ right arm rises until his hand is palm up and at a ninety-degree angle with the floor. He can almost see the faint glow of the mark underneath Cas’ clothes. 

And when Cas turns around, his eyes aren’t the warm shade of blue that Dean falls asleep to every night. Wisps of white curl around the inky black of Cas' pupils and his eyes are cold. 

“Close your eyes.” The voice echoes around them and it sounds like Cas, but it’s not Cas, Dean doesn’t recognize this creature, this being, but he does recognize the white light gathering in the palm of Cas’ hands. 

He throws his arm up over his eyes, just in time. Blazing heat washes over his skin, and Dean suspects that he’ll have a hell of a sunburn, despite it being mid-February. A shrill ringing sets in his ears. Underneath it, on a lower register, he hears the sounds of screams, and underneath that, the awful sound of flesh sizzling. 

It feels like it takes hours, but it’s probably only seconds, before the heat pulls back and Dean feels like he can breathe. Next to him, he hears Sam’s harsh, quick pants, and Eileen’s ragged gasps. He hesitantly blinks open his eyes and sees--

Cas stands in in the middle of the room. There are no vampires in sight. 

But what there is, Dean finds, is a fine, black ash that crumbles away at the touch. He rubs a little between his fingers and tries not to gag when he realizes...that was a person once. This was a flesh and blood body, and Cas...Cas vaporized them. Like they were nothing. 

But it doesn't hit him, just how far things have gone, until he makes it to the other side of the room. 

The door doesn’t want to open, but Dean forces it with a decisive shove of his shoulder. Inside are...He gags and ducks his face into the curve of his elbow. Intellectually, he knows that these used to be human bodies, but their features are warped and twisted beyond recognition. Gaping eye sockets peer accusingly at him and Dean can just catch a glimpse of what looks like screams of pain on their mangled faces. 

“Feeders,” he finally realizes with a sick twist of horror. He feels, instead of sees, Cas behind him and he turns around. Cas peers inside the room, an innocent sort of curiosity on his face. His eyes...his eyes are empty. “Cas, these were feeders!” Dean shouts, pointing at the five corpses in the room. “They were _human_! They probably didn’t have a choice in being here, they were...” His voice catches on the last word. “Innocent.” 

Cas tilts his head. There’s a disconcerting expression of confusion on his face, like he’s honestly trying to understand what Dean is saying, but it’s just not making sense to him. 

“They were tainted. They weren’t human, not really. Not anymore.” Something resembling compassion lights on his face. It looks like a contortionist trying a new pose. “They didn’t suffer, if that’s what you’re worried about.” 

Dean gapes. “They didn’t...” He gestures behind him, just barely managing to keep his gag reflex down. “They had time enough to be afraid, which means they had time to suffer!” Uncaring of the consequences, he pushes a hard finger into Cas’ chest. It’s like poking a brick wall. “We don’t kill these people, we _save_ them! That’s what we’ve always done--”

“And how has that worked?” 

Castiel asks the words without malice. There’s an amused note in his voice. “How has saving people worked for you?” 

When Dean has no answer, Castiel tilts his head. “There’s a better way. I’ll show you.” 

Dean closes his eyes because he’s heard those words from Cas before, he’s heard them in his nightmares--

When he opens his eyes, Cas is gone. 

\---

"Maybe he didn't mean to," Eileen says. 

"Dean, he saved our lives," Sam says. 

Dean clenches his jaw and pushes down on the gas pedal. 

They make it to the bunker and Cas isn't there. 

Dean goes to sleep alone and tries to ignore how cold his room is. 

\---

It's three days before Cas comes home. 

Dean wakes up in the middle of the night, spurred on by something he doesn't understand. He slides his feet into his boots and a jacket over his shoulders. He hesitates, before he grabs the shotgun sitting beside his bed. 

The bunker is quiet. Sam and Eileen are off on another hunt and Cas...Well, that's the problem isn't it? 

Dean walks past the shadowed lumps of their furniture. He can feel an urging in the back of his mind, like an itch he just can't manage to scratch. It tells him to go outside, but Dean hasn't survived this long by being stupid. On his way out the door, he tucks an angel blade into his waistband. 

The night is cold. Tiny diamonds of frost decorate the blades of grass growing just outside their door. The stars glitter above him, distant and unfeeling. Gun held against his shoulder, Dean turns slowly on the spot, scanning through the trees for whatever it was that brought him out here. 

"Dean." 

At the sound of that voice, Dean whirls around. The gun never drops and he ends up pointing a gun straight at Cas. 

Cas whose hair is wild and disheveled. Cas, whose eyes are wide and pleading. 

Cas, whose coat is stained with blood.

Dean doesn't drop the gun. 

"See that you got your wings back," he says instead. He doesn't step backwards when Cas takes a halting step towards him, but it's his own will and not instinct making that call. "Were you planning on sharing that with the rest of the class or?" 

Cas' face twists. "Dean, I don't know...I can't..." He's holding his right arm close to his body, protectively. His eyes are imploring as they look to him, but Dean can't stop seeing those faces, twisted in agony, can't take his eyes away from the spattered blood on the hem of Cas' coat. 

Cas stumbles forward, ungainly in a way that Cas never is. "Dean, please," he breathes, just before his knees buckle and he falls into the gravel outside the bunker. 

\---

Dean half carries, half supports Cas inside. 

The angel blade bumps against his back like a warning. 

He strips Cas in efficient, perfunctory movements, ignoring the shivers that chase themselves through Cas' body, the same way that he ignores how Cas clutches his right arm close to his belly. Whenever Dean comes close, an involuntary snarl crosses Cas' lips before he chases it away. 

Dean puts Cas in the bath, because that's the only thing he can think of to do. Cas sighs when he steps into the steaming water. As he sinks further into the tub, his eyes drift shut. There's no need for it, but Dean picks up a washcloth and runs it along Cas' shoulders and chest. When Cas leans forward, he washes down his back. He pours water over Cas' head and works shampoo into a lather. 

Neither of them speak. In the corner of the room, Cas' coat sits like an accusation. 

"So where did you go," Dean finally asks, when Cas' hair is wet and plastered to his face. 

Castiel flinches at the question and draws his knees up close to his chest. "I don't want to talk about it." 

Anger flares, but it's muted by the quiet terror that Dean's slowly been drowning in for days. He leans forward until his forehead rests on the damp skin of Cas' shoulder. Underneath the water, he can make out the lines of the Mark on Cas' arm, until Cas twists his arm to hide it from him. 

"Cas," Dean finally breathes, feeling like Cas is slipping through his fingers, as temporary as the water cupped in the palm of his head. "Cas, I'm really scared." 

When Cas finally reaches out to him, it's with his left hand. 

"Me too," is all he says. 

\---

So they don't bring Cas on hunts anymore. 

More and more bodies pile up around them, and Cas sits at home in the bunker. He doesn't wear his trenchcoat anymore. Dean doesn't know what happened to it. 

He knows that sometimes he'll look for Cas and he won't be able to find him anywhere. He knows that sometimes, he'll wake up from a dead sleep to Cas curling himself around his body, cold and desperate, and Dean will smell something on him...ash and smoke, copper and rot...and Dean will choke back the automatic gag reflex and open his arms, let Cas bury his face into his neck. 

"I'm sorry," Cas says one night, ragged and awful, his hand working beneath the waistband of Dean's pants, like it's the only kind of apology that he knows how to give. "I'm sorry, Dean, I'm sorry--"

And Dean never pushes him away, not even when his gorge rises at the thought of what Cas has been doing, not even at the thought of himself, hardening in Cas' bloodstained hands--

"It's ok," he says, running his fingers through Cas' hair, kissing at the damp corners of his eyes. "Cas, it's ok, it's ok--" 

He comes, wretched and empty, and in the morning, when he wakes, Castiel is gone again. 

\---

"How do we contain him?" Sam asks. 

"Could you take his grace?" Eileen asks. 

Dean shakes his head. "I don't think that would solve anything--When I had the Mark, I was still human and it was still affecting me. Who knows what's the Mark and what's just...If we take away his grace, I don't know that it would even take away his wings." Dean swallows the jagged lump in his throat. "For all we know, his grace is what's helping him hold out against the Mark. Take that away..." 

It's Cas they're talking about. Cas, who drank beers with him, and researched and fought with them, Cas who likes soft jazz and crunchy peanut butter and who likes to visit apiaries on their days off. Cas, who dragged Dean behind the shelves of the library weeks ago and whispered _Be Quiet_, before he dropped to his knees and blew Dean with Sam and Eileen just a room away. 

Cas who Dean hasn't seen in a week. Cas, who takes longer and longer to come back to himself. 

The three of them sit in silence. A gloomy pall descends and Dean can't believe that just six months ago, all four of them were in this room, laughing and debating about which movie to watch. 

It's Sam who breaks the silence first, the words drawn out of him like poison. 

"How do we shut him down?"

\---

A month later, and Dean hasn't seen Cas but once. 

And Sam is bleeding out in front of him. 

Eileen is firing, shells flying around her as she glances back over her shoulder at Sam. Desperation and grief are already plastered over her features as she shoots at the wolves who have them surrounded. Every so often, Dean hears a yelp, but they're running out of ammo and Sam is running out of blood. 

_Cas_, he prays, his stomach dropping down to his knees, _Cas, if you can hear me, Sam's hurt real bad and we need_\--

He opens his eyes into a pair of pure white pupils ringed with a thin circle of glowing blue. Even underneath his shirt, Castiel's mark glows a pale silver. 

"I always hear you," Castiel says, but it's not him. 

He lays a single finger on Sam's forehead, and Dean watches as his little brother's body knits back together. Then he watches Castiel stand. 

"Cas, no," he tries, but his voice is lost in the high ringing. "Cas!" He remembers the dust that covered every inch of that house, the corpses who had just enough time to know what was coming--

"I'm saving you." Castiel's voice carries even over the ear-splitting howl of the Mark. "I will save you and I will save this world. And then, you'll know peace." 

He's punctuated by a series of small pops. Dean furrows his brow in confusion--It's not gunfire, he knows what that sounds like, but what it could--A wolf bursts into the room, fangs bared in a vicious snarl. Castiel turns towards it, a vaguely amused look on his face. He doesn't move as the wolf rushes him, claws outstretched, and Dean's about to scream at him, tell him _Cas, get the fuck out of the way_\--

Before the wolf ever has a chance to reach Castiel, he falters. Confusion crosses those features, then horror, then--

Dean wants to scream as he watches the wolf's face _bubble_, for just the briefest moment, and then--

Blood spatters as the wolf's head _explodes_, showering Castiel, Dean, Eileen, and Sam with gore. 

The wolf's body drops with an empty thump. A thin trickle of blood trails from the ragged stump of his neck. 

Castiel rotates, his face peaceful. "I told you Dean," he says, unconcerned with the filth dripping from his fingers. "I will save you and the rest of this world." His expression hardens as he looks at their identical, horrified, expressions. "Please don't get in my way." 

\---

It makes a horrible sense. 

The Mark of Cain turned its bearer into something like The Darkness--amoral, bordering on evil. Warped by Lucifer and Cain, it dug its bloody claws into the user until they became a demon. 

Cas' mark...Works differently, but on the same premise. 

It's slithered around Cas, around his grace, and turned him into something...unfeeling. Righteous without compassion or empathy. 

A savior of the world. 

But one that no longer remembers how to love. 

\---

Three days later, Dean finds Cas curled up in an armchair in the library, thin blanket clutched around his body. He's rocking back and forth, nose flaring with his attempts to breathe. "Dean," he gasps, body curled around his right arm, "Dean, I can't stop it, I can't...Dean, _please_\--"

And Dean drops to his knees and tries to wrap himself around Cas the best that he can, telling him all the while, _It's going to be ok Cas, we're going to be ok_, even though he hasn't believed that for a long time. 

\---

"I found how to make one," Sam says a few days later, after Castiel disappears again. "A Ma'lak box." 

"Shut the fuck up," Dean says, pushing past him. "It's _Cas_. We just need to figure out how to contain this, how to work around it..." He doesn't believe the words as he's saying them. 

He knows what he has to do. He's known for a while.

"Dean." He hates the softness in Sam's voice. "He's not the same, and you know it." 

"You never gave up on me," Dean says, teeth bared in a snarl. "When I had the Mark and I was...You never gave up on me." 

Sam doesn't have an answer for that, but Dean can also see that he hasn't managed to change Sam's mind. 

"I love him," he tries, his voice wobbling pathetically on the middle syllables. 

"I know," is all that Sam says.

\---

A month later, and he comes across Cas, almost on accident. 

"Cas, you can stop this." Castiel takes another step forward. Dean can't find any trace of the angel that he loves in his blank features. "Cas, you don't have to...They're innocent Cas." He gestures to the small group huddled behind him. "They're humans!" he tries, when Cas doesn't stop. "Cas, they're innocent!" 

Castiel finally looks his way. There's a condescending pity in his eyes. "There's no such thing," he tells Dean, like he's a particularly difficult child. He nods towards the group. "I've seen their futures. They will be turned; they will become monsters. I'm just stopping the problem before it begins. Now please. I have no wish to harm you." 

"Cas, please," Dean begs, fear seeping through him. "We can stop this." 

Cas tilts his head to the side, so reminiscent of his former self that it makes Dean want to sob. "Stop this? Why would I want to?" 

Castiel steps forward again. When Dean tries to put himself in his path, on some final attempt to save these people, Castiel just reaches out. Dean tries to dodge, but Cas' fingers land square on his forehead. 

\---

Dean wakes in a puddle of drying blood. 

Castiel is nowhere to be found. 

And Dean finally, finally, understands what it is he has to do.

\---

Dean startles awake in his room. It's pitch black, but he can feel another presence in the room with him. 

"You're making a Ma'lak Box," Castiel says, his voice dispassionate. "You're going to lock me away." 

Dean swallows. The sheets are gathered around his waist and his nearest weapon is across the room. Not that he thinks anything as mundane as a blade would work on Castiel. Not anymore. 

"It's all I can think of," Dean confesses. He twists the blanket in his fists. "Unless you can think of a way to stop." 

"I won't." Castiel turns to him. In the darkness of the room, his pupils glow an ethereal white. Dean sees the pulsing of the Mark underneath Cas' arms. He can also see the faint, silvery lines stretching out from it, like taproots growing deeper into Cas. 

"Cas, please." He's close to tears, but he can't...to come this far and _still_ lose..."Cas, you have to stop. There has to be another way." 

"There isn't." Castiel's eyes move closer and Dean tenses. 

He's afraid of Cas. For the first time, in years, he's afraid of what Cas could do. 

Castiel notices. He notices everything these days. He stops, just short of the foot of Dean's bed. 

"I'm losing hours," he murmurs, still contemplative. "I wake up in strange places and I don't know how I got there. I wake up to screams and I don't know whose they are. I know that I've hurt people. People who deserved it and people who didn't." The white in his pupils wisps away, leaving them both plunged into darkness. "It was good in the beginning," Castiel whispers. This time he sounds like his old self, the rasp in his voice a soothing balm against the aching wounds of Dean's soul. 

"The intentions were always good, but somewhere along the way..." 

"Cas, come here," Dean breathes, and Castiel comes. 

He kisses Cas then, with a ferocity bordering on insanity. He clutches Cas tight to him, and every time that the tendrils of white threaten to creep back into Cas' pupils, he kisses him harder. Cas gasps into his ear, shedding his clothes in the darkness. In the darkness of the room, his mark glows with an obscene gentleness. 

Dean reaches out to touch it, remembering the first night, how innocuous he'd thought it then, how triumphant he'd been... "Don't." Cas pulls away from him, arm held close to his chest. "Dean, please don't." 

"All right, it's all right." Dean pulls Cas down and into him, ignores the hollow spot in his chest that grows bigger the more he tries to fill it with Cas. 

He takes Cas in his hand, listens to his soft cry of pleasure. He spreads his legs, lets Cas slot against him, enjoys the heat of their bodies. "Inside," he says, pressing the lube into Cas' hands, "inside, please." 

Cas' fingers work inside him, a little too fast to be entirely pleasurable but Dean doesn't care. It's enough to feel Cas' body against him, enough to lift his head in a silent request for a kiss and have it granted. He tells himself it's enough, even as the canyon inside him grows. Cas pulls his fingers away and Dean whimpers with loss. 

"I'm here," Cas says, nipping at Dean's chin as he settles himself back between Dean's legs. He lifts Dean's knees up, holding him open, as blunt pressure pushes against his hole. Then, Cas slides inside him, and Dean groans in relief. "I'll always be here, I promise Dean, I'll always be with you, even after--"

"Shut up," Dean says fiercely, locking his ankles at the small of Cas' back and pushing him forward. "Just shut up," he pleads, a single tear slipping down his cheek at Cas' soft gasp. 

And Cas fucks him, by turns tender and brutal, until Dean is panting underneath him and trembling with the need to come. "Please, please, please," he whispers, fisting a hand in Cas' sweat-damp hair. "Please Cas, please--" 

Cas' hips snap into him as his hand closes around Dean's cock. "Anything you want," he promises Dean, as he jacks him in sloppy strokes, and even as Dean comes with a loud wail, he thinks _I want you, I want you forever and ever_\--

Cas collapses on top him, trembling with the aftershocks. He drags Dean closer as he buries his face into Dean's chest. Unable to fathom letting go, even for a second, Dean holds him close. He traces designs over Cas' back, runs his fingers through his hair. 

"I love you," Cas finally whispers, and it sounds like _goodbye_. "I've always loved you, since the moment I saw you, I've loved you, I'll never stop, never..." 

"Cas please," Dean chokes out. "Please help us. There has to be something else that we can do, some spell...I can't lose you," he admits, finally letting his tears fall in a steady stream. "I can't...I can't do any of this without you." 

Cas lifts his head, the point of his chin digging into Dean's sternum. Cold adrenaline runs through Dean's veins as he notices the tendrils of white creeping along the edges of Cas' pupils. 

"You have to finish the box." Already some of the warmth of Cas' voice has bled out. "Dean, if you ever loved me, even the slightest, please." Cas shudders and pulls away from Dean, leaving his skin chilled and bereft. "Please don't let me become something that you hunt." 

"Cas--" Dean stretches out, but Cas is already gone, leaving his _I love you_ hanging after him, a pathetic offering to an uncaring god. 

\---

And Dean doesn't see Cas after that.

\---

A month later, and he's standing on the deck of a ship. It's bucking and heaving in the surf and if Dean weren't already nauseous, that would be the trick. He's already vomited twice this afternoon; his stomach has nothing left in it to offer. 

The box sits on the deck, open like a grave. 

"Cas?" Dean whispers. Rain pelts him across the face as the wind stings his vulnerable skin. In the distance, lightning flashes across the sky. "Cas, can you hear me?"

A month of trying to figure out which massacres were Cas and which were monsters. A month of living in constant fear that he would see Cas, a month spent longing for him. A month in which the knowledge settled in--whatever Cas used to be, that's gone. Whatever kind of a future he could have had...That's gone too. 

"Cas, if you can hear me, I need to see you." 

He hopes Cas doesn't answer. He hopes that the Mark, with its sly, wily survival instinct, tells Cas to run, run run from his shoddy trap. He hopes that Cas stays far away and that this whole trip ends up with an empty box and a wasted $50. _Please Cas_, Dean thinks, in his darkest of places, _please don't come_. 

"You made it." 

Dean whips around. Cas is on the other side of the deck. His hand grips the railing and Dean doesn't know if it's to keep himself from falling over, or to keep himself from attacking. A feral, otherworldly light spills from him. 

"Please don't make me do this," he whispers. "Cas, please go." 

The lines of silver are stronger. They've grown further. Some even snake up past Cas' shirt collar, to curl coyly around the edge of his jaw. There's hardly a ring of blue anymore around the pulsing white light of Cas' pupils. 

"I killed a young girl this week," Castiel tells him. He steps away from the railing. "She couldn't have been more than seven, and I don't know why I did it. She wasn't a monster. But I looked at her, and I _knew_...she had to die." 

"Cas. Please. Go." 

"I killed a family of werewolves. They begged for their lives, said that they never hurt a human, they only ate animals...and I think they were telling the truth. But it didn't matter, because I _knew_ that they had to die. I never hesitated, not even when the mother flung herself in front of her children." 

"Cas, stop it. I know what you're doing, now stop it! Go!" 

Cas doesn't stop until he stands just in front of Dean. "I thought about killing Sam. He's tainted; demon blood runs in his veins. There's no place for Sam in a perfect world." Dean trembles. "I thought about how easy it would be. You don't know how powerful I am now; I could end Sam's life with a thought. A mere flip of my fingers. And then..." 

"Shut up." 

"Would you let me do it?" Cas tilts his head as his thumb ghosts across Dean's lower lip. "Just because you believe in me? Would you let the world burn, to save me?" 

"Yes!" 

Louder than thunder, Dean's voice splits the night. Tears fall from his eyes, indistinguishable from the rain falling down. "There's still some part of you left in there, because if you were really going to do those things, then you would have done them already!" He fists a hand in Cas' damp shirt and drags him in close. "If there's still a part of you left, it means that we can fix this!" 

It's always worked out before, every time--They've stopped Lucifer, and the Apocalypse, and the Darkness, and God himself--He can't lose Cas, not now--

"Dean." The white fades from Cas' eyes, leaving him smaller. He stumbles forward, into Dean's arms. "Dean, please." 

"We can fix this," Dean says into the top of Cas' head. "We just need more time." 

"Dean, you don't believe that." Cas sounds exhausted, defeated. "Otherwise, why would you be here with the box?" He pulls away from Dean's embrace, though he rests his palm against Dean's cheek. "It has to be now. Now, when there's still a part of me that will _let_ you put me into the box." He shudders as he looks at the dark, yawning mouth. "Otherwise...you'll never put me in there, and all those things that I said...They _will_ come true, because there won't be enough of _me_ to stop them." 

Dean shakes his head, presses his lips to Cas' palm. "There has to be another way, it can't...It can't end like this. There has to be another way." He looks at Cas, pleadingly, because Cas always has the answers, Cas always takes care of him...There's nothing but a bleak acceptance in Cas' eyes. 

"I love you," he says, a futile, desperate attempt to stave off the inevitable.

Cas' smile splits Dean's heart in half. "I know." He holds Dean's face between his hands, presses a kiss to his forehead. "That's why you have to do this. Please. You have to...You have to save me, one last time." 

"No." Dean shakes his head, denying even as Castiel walks them backwards towards the box. "No, you saved me. You saved me every single time." 

Cas' heels bump against the side of the box. "Then it's your turn to the return the favor. Please. Please do this for me." 

Cas steps into the box and Dean shudders. "What am I supposed to do without you?" he asks. He holds onto Cas' wrists with a death-grip, keeping Cas' hands on his face. "How am I supposed to do any of this without you?" 

"I don't know." Cas presses a lingering kiss to the pulse point of Dean's wrist. "But if you don't do this...Then everything that you love will be destroyed by a monster who wears my face." He kisses Dean, slow and gentle, his teeth catching on Dean's lower lip. 

"Dean." Hours pass, days, years. What does it matter? Cas is here, with him, he'll wake up and this will all be some awful dream--

"Dean, you have to let me go." 

_I'm not strong enough_, Dean wants to say, but his hands loosen anyway. 

Cas smiles at him, and it's the same smile that Dean fell in love with, the same that he would wake up to, the same that peered up at him when he was falling asleep in the middle of a movie, the same smile--

Cas lowers himself into the box. 

And there's still time, they can still fix it, there has to be a way...Cas' eyes close and for a second, he looks almost peaceful--

Cas' eyes snap open, pure white and narrowed in an expression of hatred that Dean's never seen before. Cas' lips curl back in a snarl, and he can feel power gathering--

Dean slams the lid closed. 

The sound echoes through his skull. 

For a second, he stares at the box. Its sigils flare to life as the locks seal. He thinks that he might pass out. He's sick, woozy, unable to comprehend what he's done--

"Dean! Open the box right now Dean!" 

And it's not Cas that's asking. 

Trembling, Dean starts to push the box towards the open bow of the ship. Beneath him lies the expanse of the ocean. He'd thought that one day, this would be his fate, that it would be Sam and Cas putting him two miles underneath the water. But now, it's Cas' voice that he hears echoing as the metal scrapes against the deck of the ship. 

"Dean! Dean, please! Dean, it's me, please! Let me out! Dean, don't do this!" 

Dean falters, knee striking the deck. That's...it's _Cas_, and Cas is terrified, Cas is pleading--

"Dean, please help me! Dean, I don't want--I don't want to go! Please Dean, please, please--" 

But Cas would never beg for his life. Cas would never...Cas has always seen the truth of the situation and known what had to be done, even when it was hard, even when it was impossible. Cas would know what had to be done. 

And no matter how much he wants it to be otherwise, Dean knows what has to be done too. 

Another shove has the box teetering on the edge of the deck. Below, the waves crash with fury. Inside the box, Cas says, "Dean. Dean, I love you. Please don't...Don't we deserve some kind of happiness? You said that it didn't have to end like this--"

"It shouldn't." Dean drops to his knees and puts his cheek against the cool metal of the box. "It's not fair and it shouldn't end." A sob catches in his throat as Cas' fists bang against the lid of the box. "Cas, if you're still in there somewhere, if you can hear me...I'm so sorry. I'm so, so sorry." He lays his palm flat against the box, imagining that he can feel the heat of Cas' skin through the layers of magic and metal. "I love you. I love you so much." 

"Dean, please--"

With one last convulsive shove, Dean sends the box off the edge of the ship and into the ocean below. 

\---

Afterwards, he sits and watches the waves. 

The boat rocks back and forth. Dean doesn't try to move it out to calmer waters. It would serve him right if he were to tip overboard as well. Then, he could end up on the bottom. Settle next to Cas. 

The storm roars itself out just as the sun comes up. The waves quiet and calm, leaving the ocean a smooth, glassy surface. 

Somewhere, beneath the water, the man that Dean loves is imprisoned until the end of time. 

And Dean's the one who put him there. 

He throttles up the boat and heads back towards the shore. 

\---

_Cas? Cas, I'm not sure if you can hear me, but if you can...Fuck. I don't know what to say. I'm sorry. I'm so sorry._

\---

_Eileen died Cas. We couldn't get to her in time, and she...I can't do this anymore. Hunting. It's over. We lost._

_I lost._

\---

Sam clatters into the room, jostling Dean out of his latest prayer. They're not even prayers anymore, just a stream of consciousness sent in Cas' general direction. If there's any part of Cas that's still lucid enough to understand them, then Dean figures it's worth the effort. And even if that's not the case...He can't stop. It's his one last link to Cas, and he can't bear to cut that off. Not after everything that they've lost. 

"I'm going," Sam announces, but it's not because he thinks he can win. It's because he hopes that he'll lose. 

They're the same, him and Sammy. It's just that Dean has one more thread tethering him to the world than Sam. 

_Going on a hunt now. I know that I said I wasn't going to anymore, but Sam's itching to get himself killed, and I can't...I can't lose him too._

_I love you Cas. If Sam gets his way, then I might be able to say it later. Just know...I love you. Always will._

Dean packs his duffel. He pictures a happier world, one with Claire, and Donna, and Garth, and Eileen. One where he and Cas can still share a drink at the end of the day. 

One where there's still hope. 

\---

**Author's Note:**

> Come and yell at me on tumblr [here](https://dothwrites.tumblr.com/). I write nicer, happier things there too.


End file.
